The present invention relates to a connector for interconnecting or mutually isolating two or more electrical circuits. There is a requirement for electrical connectors that can be used safely in applications where they may be exposed to explosive atmospheres. Such applications are found in industrial plants, for example, in the oil, gas, petrochemical and mining industries. The explosive atmosphere may be due to the presence of explosive gas, liquid, vapour, or combustible powder or dust (e.g. grain dust, mineral dust or powder etc.).
Industrial plants are categorised into zones according to the likelihood of explosive gases being present. Various protection measures are adopted to prevent explosion and the International Electromechanical Commission (IEC) has established standards relating to equipment for use in explosive atmospheres such as, for example, IEC 60079. Connectors in accordance with the standard should be capable of being used in an explosive atmosphere such that if two interengageable connector elements of the connector are separated and a spark is generated, any resulting explosion is contained within the connector structure and is prevented from being transmitted to the surrounding environment.
The IEC 60079 standard stipulates that plug and socket connectors should be interlocked mechanically so that they cannot be separated when the contacts are energised (i.e. when power is still being supplied to the connector elements). Alternatively the connector elements may be secured together by means of special fasteners and marked with a warning such as “do not separate when energised”.
The IEC 60079-0 standard provides for less rigorous criteria in relation to connectors that are rated for currents not exceeding 10 A and voltages not exceeding 254V a.c. or 60 V d.c. This standard requires that plugs and sockets are separated with a time delay such that the rated current flow ceases and any arc is extinguished prior to separation. The plug and socket should remain flameproof to IEC 60079-1 during the arc quenching period. Plugs remaining energised when not engaged with a socket outlet are not permitted.